Dr. Maria Monica Gramatges is an Assistant Professor of Pediatrics at Baylor College of Medicine (BCM) and Texas Children's Cancer Center. She is currently supported on a K12 grant and is completing her Master's degree in Clinical Investigation. Her Clinical Research Mentor is Dr. Sharon Plon, a leading cancer geneticist, and her Basic Science Mentor is Dr. Alison Bertuch, a leading telomere biologist. Dr. Lisa Bomgaars and Dr. Michael Andreeff, faculty experts in clinical trial design and leukemia molecular biology, respectively, are on her advisory committee. Support from the K23 award will enable Dr. Gramatges to gain additional research skills and receive mentorship in authoring publications and developing research grants while performing her research project. Dr. Gramatges' goal is to become an independent investigator and leader in pediatric oncology translational research. In this application, Dr. Gramatges is studying the role of telomere biology in acute myeloid leukemia (AML) and treatment-related toxicities. Telomeres are repetitive DNA-protein structures at chromosome ends which protect chromosome integrity. Telomeres shorten with DNA replication, causing increasing cellular chemosensitivity and susceptibility to genomic instability. Telomere biology disorders, including dyskeratosis congenita, are due to germline missense and truncating sequence mutations in telomerase-associated genes and are associated with a spectrum of problems including aplastic anemia and a strong predisposition for myelodysplasia and AML. These sequence changes are also enriched in adults with hematologic malignancies, though no studies have explored their association with pediatric AML or treatment toxicities. Dr. Gramatges has generated significant preliminary data and developed collaborations at BCM, MD Anderson Cancer Center and through the Children's Oncology Group to answer two related questions (1) what proportion of children with AML harbor short germline telomeres and/or deleterious germline variants in telomerase-related genes and (2) does telomerase deficiency and/or short telomeres increase the likelihood of persistent bone marrow suppression and other toxicities characteristic of telomere biology disorders. She will test these questions by (1) clinically and functionally characterizing telomerase variants and determining their frequency in a local cohort of pediatric AML compared to controls (2) retrospectively comparing the proportion of deleterious telomerase variants and/or short telomere length in uniformly-treated pediatric AML patients with delayed vs. expected bone marrow recovery, and (3) prospectively determining the incidence of deleterious telomerase variants and short telomere length following chemotherapy in pediatric and young adult AML patients and correlating these results with specific treatment complications. Aim 3 is the first study to evaluate the effects of telomere biology on toxicities and outcomes in AML. Results of this research will support future work on a biological correlate to a consortium treatment study, and may result in screening, closer toxicity monitoring, and therapy modification, thereby reducing AML treatment-related morbidity and mortality.